This invention relates to magnetron apparatus for use in microwave ovens, defreezers, radars or the like.
Magnetron apparatus generates microwaves at high efficiencies so that it is used in various fields of application.
Generally, magnetrons, source devices fans, etc. are manufactured and assembled in different factories. A magnetron oscillator generally comprises an anode cylinder, a plurality of vanes extending from the inner wall of the anode cylinder toward the center thereof, a cathode electrode positioned at the center of the anode cylinder, permanent magnets for passing magnetic flux in the axial direction of the anode cylinder through an interaction space defined by the cathode electrode and the vanes, and an antenna for deriving out a microwave output from the magnetron. Thus, the magnetron oscillator is manufactured and sold as one unit like a vacuum tube, a transistor or the like. Accordingly, the maker of magnetron apparatus selects a magnetron oscillator having desired characteristics suitable for a particular application. For this reason, the maker of the magnetron apparatus is obliged to change the design of its apparatus to suit the characteristics of the magnetron oscillators available on the mark. On the other hand, the maker of the magnetron oscillators are required to manufacture magnetron oscillators of many types by the request of various makers of magnetron apparatus. Accordingly, it is the present practice that the makers of the magnetron oscillators manufacture oscillators for general use and that the makers of the magnetron apparatus modify their design to match its characteristics to those of the magnetron oscillators. The compromise described above between the makers of the magnetron oscillators and the apparatus utilizing the same imposes strict condition to the makers of the magnetron oscillators, i.e., the electric characteristics, efficiency, structural limits, etc. Accordingly, the makers of the magnetron oscillators are required to manufacture their magnetron oscillators and the component parts thereof at considerably high accuracies so that cost reduction of the product has been difficult. For the same reason, limits have been imposed upon the characteristics of the devices manufactured by the apparatus makers such as the capacity of the capacitance, the voltage-current characteristic of the boost transformer that constitute the source circuit of the magnetron oscillator.
Further, a magnetron oscillator is generally incorporated with a filter which is used to eliminate undesirable waves from transmitting to the outside from the filament terminals, and such filter has also been manufactured by the maker of the magnetron oscillator. Such magnetron oscillator is disclosed in U.S. Pat. No. 3,846,667 to Hisada et al, dated Nov. 5, 1974.
A source circuit including a transformer for applying high voltage to the anode electrode of the magnetron, a rectifier, etc. has been assembled and combined with a magnetron oscillator by the apparatus maker. A fan sending cooling air to the heat radiating fins of the magnetron has also been combined with a magnetron oscillator by the apparatus maker.
As above described a magnetron apparatus is fabricated from a number of component parts so that when the maker of the magnetron oscillator tries to combine a source circuit and a fan with a magnetron oscillator a long wiring may be required between the oscillator and the source circuit since it is often necessary to change the layout of the component parts. Further, since the fan must be located near the magnetron, it is necessary to use a special support for the fan. Moreover, since the fan and the source circuit are manufactured as independent units from the magnetron oscillator, they require additional spaces in the assembled magnetron appartus. The source circuit comprises compound parts generating considerable amount of heat such as a high voltage transformer and capacitor and these component parts are designed to be cooled by natural cooling so that these component parts operate at relatively high temperatures which greatly affect the operating characteristics of other electric elements.